KR100592780B1 - The negative type liquid photoresist for the use of Roll Coater. - Google Patents

Abstract

The present invention provides a negative type liquid photoresist in order to solve the problems caused by using a dry film as a solid photoresist in the photo process in the conventional PCB (Printed Circuit Board) manufacturing process. In addition, the conventional negative liquid photoresist has a short shelf life, does not have excellent fine wire adhesion or resolution, has a poor coating property, and has problems such as pinhole defects. The present invention solves the above problems and provides a negative type liquid photoresist with a longer shelf life (12 months) than conventional products (3 months).

Photoresist, negative type, photoinitiator, resolution, exposure

Description

Negative liquid photoresist for roll coaters. {The negative type liquid photoresist for the use of Roll Coater.}

1 is a graph of the GPC measurement (molecular weight measurement) of the base polymer.

2 is a detailed graph of FIG.

Figure 3 is a UV wavelength vs. light absorption measurement graph of the base polymer.

<Description of the code | symbol about the principal part of drawing>

The present invention relates to a negative type liquid photoresist (LPR) for a roll coater used in manufacturing a printed circuit board (hereinafter, referred to as a PCB). It is related to LPR which has improved resolution, longer shelf life and no tagging after drying.

Photoresist (hereinafter referred to as PR) is a photosensitive material used to form an image on a substrate. After the PR coating layer is formed on the substrate, the coating layer is exposed to an activating light source that has passed through the photomask. Then, the coating layer in the region where the light passes through the photomask is chemically modified and the coating layer in the region where the light is blocked by the photomask. No chemical modification takes place. This transfers the pattern of the photomask onto the PR coated substrate and obtains a Relief image that allows selective processing of the substrate.

Dry film resist (DFR) is mainly used to form circuits on PCBs, but high resolution photoresist (PR) is required due to the miniaturization of PCBs and miniaturization (integration) of circuit lines. DFR has a limitation in responding to the above requirements due to its characteristics (solid, film thickness of 20㎛ or more), and has many causes of defects during the process (pinhole deterioration of adhesion to the substrate), and it protects DFR during laminating. Due to the hassle of peeling off the PET film, the work speed is slow and the price is expensive. Therefore, in order to solve the problem of the DFR these days, the liquid PR (Liquid Photoresist, LPR) is a trend to use. LPR of the present invention has the advantages shown in Table 1 compared to the DFR.

Coating of LPR on the substrate includes a roll coating method, a screen method, a dipping method, a curtain method, a spray method, and the like. It is preferable to use for roll coating. When the LPR of the present invention is used for roll coating, a general Litho process may be followed. That is, what is necessary is just to progress in order of coating, drying (temperature 80 degreeC, 2 minutes), exposure, and image development.

However, in the conventional LPR, adhesion to the substrate is weak when coating, tagging occurs when the substrate is laminated after drying, and there is a problem in that resolution is degraded during development and corrosion.

In addition, the conventional LPR has a short retention period (3 months), the price is expensive, the manufacturing cost rises.

The present invention solves the problems of the conventional LPR as described above, the shelf life (storage stability) is longer than the conventional LPR (12 months or more), the resolution is improved, the adhesion to the substrate is excellent, the substrate laminated after drying Provides LPR that does not cause tacking.

TABLE 1

An object of the present invention is to solve the problems of the conventional LPR described above, in order to achieve this object, in the present invention, the base polymer represented by the formula (1) is 20 to 23% by weight, a photopolymer monomer represented by the formula (2) Pentaerythritol caprolactone hexa acrylate is 10 to 16% by weight, the photopolymerization initiator represented by the formula (3), (4) to 12% by weight, and other additives provide an LPR composition characterized in that consisting of 3 to 5% by weight. .

The present invention will be described in detail as follows.

The present invention describes the properties and roles of the respective component materials in the LPR mainly containing a base polymer, a photopolymerization initiator, a photopolymerization monomer and an additive.

Base polymer itself has no photosensitivity, and according to the average molecular weight and distribution (see Figs. 1 and 2), the hardness, adhesion, development, peeling, peeling, It plays a role in determining the most basic physical properties such as Shelf Life and Resolution.

Photoinitiator plays a role in giving photosensitivity to LPR. That is, the photoinitiator, when irradiated with light, imparts chemical activity at a low wavelength band (see FIG. 3) of the base polymer, thereby making the LPR photosensitive in an even region of the light wavelength.

Photopolymers (Oligomers) have a property of bonding and curing base polymers upon irradiation with light. That is, when irradiated with light, the photoinitiator imparts chemical activity in the wavelength range where the light absorption rate of the base polymer is low, and the photopolymerizer hardens by bonding the base polymer.

Depending on the properties of the base polymer, the photopolymerization initiator, and the photopolymerization monomer, when LPR is irradiated with light, the LPR becomes insoluble in the weak alkaline developer by curing by photochemical reaction in an even region of the light wavelength. Therefore, by using the pattern of the photomask, it is possible to obtain a fine image of a positive type or a negative type required.

Additives include solvents and diluents, dyes, optical image forming agents, etc., and can be added and used according to the requirements of the LPR, such as maintaining the liquid state of the LPR, the need for post-coating inspection, and the need for circuit recognition after exposure.

Hereinafter, the present invention will be described in more detail.

Specific examples of the polymer used in the present invention are methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, butyl Acrylate, isobutyl methacrylate, ethyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, glycidyl methacrylate, acrylic acid, Methacrylic acid, monoacrylic acid, maleic acid, fumaric acid, styrene, hydroxy styrene, acrylonitrile, vinyl acetate, and the like are included, but the scope of the present invention is not limited thereto.

(R ₁ is CH ₃ or H, R ₂ is an Alkyl group having 1 to 9 carbon atoms, n is the number of polymers)

The amount of the base polymer of Chemical Formula 1 is preferably contained 20 to 23% by weight based on the total composition.

The photopolymerizable monomer used in the present invention is an ethylenically unsaturated compound, which has a monofunctional group and is crosslinkable, and a monomer having a double bond is cross-linked to polymerize a three-dimensional network having a very large infinite molecular weight. To form a structure. It has a strong physical chemical resistance against the plating solution and etching solution, and has a solvent dissolving power. In the unexposed areas, the acidic polymer is salted in the weak alkali solution, but has no effect in the exposed areas. In addition, it is decomposed and removed in a 2-4% caustic soda zone polymerized (cured) during stripping.

Examples of photopolymerizable monomers useful in the present invention include trivinylbenzene, divinyltoluene, divinylpyridine, divinylnaphthalene and divinylxylene, ethylene glycol diacrylate, trimetholpropane triacrylate, diethylene glycol divinyl ether, Trivinylcyclohexane, allyl methacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, propylene glycol dimethacrylate, propylene glycol diacrylate, trimetholpropane trimethacrylate, divinyl Benzene, glycidyl methacrylate, 2,2-dimethylpropane 1,3-diacrylate, 1,3-butylene glycol diacrylate, 1,3-butylene glycol dimethacrylate, 1,4- Butanediol diacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimetha Relate, Tripropylene Glycol Diacrylate, Triethylene Glycol Dimethacrylate, Tetraethylene Glycol Diacrylate, Polyethylene Glycol 200 Diacrylate, Tetraethylene Glycol Dimethacrylate, Polyethylene Glycol Dimethacrylate, Ethoxylation Bisphenol a diacrylate, ethoxylated bisphenol a dimethacrylate, polyethylene glycol 600 dimethacrylate, poly (butanediol) diacrylate, pentaerythritol triacrylate, trimetholpropane triethoxy triacrylate, glycerol Reylpropoxy triacrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, dipentaerythritol monohydroxypentaacrylate, divinyl silane, trivinyl silane, dimethyl divinyl silane, divinyl methyl silane Methyl trivinyl Silane, diphenyl divinyl silane, divinyl phenyl silane, trivinyl phenyl silane, divinyl methyl phenyl silane, tetravinyl silane, dimethyl vinyl disiloxane, poly (methyl vinyl siloxane), poly (vinyl hydrosiloxane), poly (phenyl Vinyl siloxanes) and mixtures thereof, but the scope of the present invention is not limited thereto.

Particularly suitable crosslinkers are dipentaerythritol caprolactone hexa acrylates having the formula (2) below.

As an acrylic ester compound having 3 to 6 functional groups in one molecule having adsorption force by adsorbing active hydrogen, one or more selected from the formula (2) is used, and preferably, the one represented by the formula (2) is mainly used. Significantly improve hardness, adhesion, long-term storage and resolution, and tacky property The amount of the photopolymerization monomer is preferably 10 to 16% by weight based on the total composition.

The photoinitiator, photosensitive generator, and photo acid generator used in the present invention are chemical (free radicals) of molecular structure within a short time in a region having a wavelength range of 200 to 450 nm by light irradiation. It refers to a composition of polymers in which physical changes occur such that physical properties such as solubility change (ie, solubilization or insolubilization), coloring, and curing of any solvent occur.

The base polymer has a photopolymerization in which the monomer is a polymer by light, and there is a photocrosslinking reaction that changes into a three-dimensional crosslinked polymer.The LPR for the scattered light and the parallel light depends on the content of the photoinitiator or the light source of the exposure equipment. It can be manufactured, energy and raw materials can be saved, and work can be performed quickly and accurately according to light rays.

Examples of the photoinitiator used in the present invention include benzoin alkyl ethers such as benzoin, benzoin methyl ether, benzoin isopropyl ether, benzoin isobutyl ether, acetophenone, 2,2-dimethoxy-2- Acetophenones such as acetophenone, 2,2-dimethoxy-2-phenyl acetophenone, 1,1-dichloro acetophenone, 4-methoxy-2,2-dichloro acetophenone, 2-methylanthraquinone and 2- Anthraquinones such as tettalbutyl anthraquinone, 1-chloroanthraquinone, and 2-amyl anthraquinone, 2,4-dimethyl thiosanthone, 2,4-diethyl thiosanthone, 1-chlorothiosanthone, 2 Thiorates, such as 4-diisopropyl thiosanthone, 2-isopropyl thiosanthone, and 1-chloro-4-propoxy thioxanthone, acetophenone dimethyl ketal, benzyl dimethyl ketal, and 2,2- Ketals such as diethoxy-1,2-diphenylethanone, benzophenone, 4-chloro benzophenone, 4,4'-bis (dimethylamino) benzophenone, 4,4'-bis (die Benzophenols such as amino) benzophenone and 4- (4'-dimethylphenylthio) benzophenone, 2,4,6-trimethylbenzoindiphenyl phosphine oxide, 2,4,6-trimethylbenzoindiphenyl phosphonic acid ester , Bis (2,4,6-trimethylbenzoin) -phenyl phosphine oxide and acrylic phosphine oxides, bis [2- (2-chlorophenyl) -4,5-diphenyl-imidazole, 2,2 ' -Bis (2-chlorophenyl) -4,4'5,5'tetra phenyl-1,2'biimidazole, 2-ethyl anthraquinone, 2- (O-chlorophenyl) -4,5-diphenyl imi Dazole dimer, 2- (O-chlorophenyl) -4,5-di (m-methoxy) phenyl imidazole dimer, 2- (O-fluorophenyl) -4,5-diphenyl imidazole dimer, 2,4 -Di (P-methoxyphenyl) -5-diphenyl imidazole dimer, 2- (2,4-dimethoxyphenyl) -4,5-diphenyl imidazole dimer, 2- (P-methyl..captophenyl ), 4,5-diphenyl imidazole dimer and 2,4,5-trianyl imidazole dimer, such as Misellaneous, 4,4 'bis (dimethylamino) Zophenone, 4,4bis (diethylamino) benzophenone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1, 2-methyl-1- [4- (methyl Thio) phenyl] -2-morpholinopropane-methyl-4- (dimethyl amino) benzoate, 2-ethylnucleosil-4- (dimethylamino) benzoate, 1-hydroxy-cyclonucleosil-phenylketone, 2-hydroxy Hydroxy-2-methyl-1-phenylpropane-1-αhydroxy and amino alkylphenones, but the scope of the present invention is not limited thereto.

The amount of the photopolymerization initiator is preferably used in an amount of 4 to 12% by weight based on the total composition, and is usually 2,4,6-trimethylbenzoindiphenyl phosphine oxide of the following formula (3), 2,2'-bis of formula (4) By containing 2-chlorophenyl) -4,4 ', 5,5' tetra phenyl- 1,2 'biimidazole, LPR for scattered light or parallel light can be manufactured according to the light source of an exposure machine.

In particular, the photoinitiator 2,2'-bis (2-chlorophenyl) -4,4 ', 5,5' tetra phenyl-1,2 'biimidazole and 4- (4'-dimethylphenylthio) benzophenone It is preferable to produce LPR for scattered light by containing 2-5 weight%.

Further, photoinitiator 2,4,6-trimethylbenzoindiphenyl phosphine oxide, 2-isopropyl thiosanthone, benzyl dimethyl ketal, .2,2'-bis (2-chlorophenyl) -4,4 ', 5 It is preferable to prepare LPR for parallel light by containing 10 to 13% by weight of, 5'tetraphenyl-1,2'biimidazole.

[Formula 4]

As solvents and diluents used in the present invention as other additives, the composition of LPR can be prepared by dissolving, dispersing (stirring) in one or more suitable solvents, and depending on the coating method, the viscosity (Viscosity) It can be selectively used according to the solid content (%), or the boiling point of the solvent, suitable solvents include ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone and 2-heptanone, Polyhydric alcohols such as ethylene glycol, diethylene glycol mono acetate, diethylene glycol, diethylene glycol monoacetate, propylene glycol, propylene glycol mono methyl ether acetic acid, dipropylene glycol mono acetate, monomethyl, monoethyl, monopropyl Cyclic ether solvents such as monobutyl, ester solvents such as methyl acetate, ethyl acetate, butyl acetate, Cells, such as solbu solbu and ethyl cells in tilsel sole class, the nitriles such as acrylonitrile.

In the present invention, the additive may be selected in consideration of reactivity, odor (health), etc. in the above mixture, and may be used as a diluent, but the scope of the present invention is not limited thereto.

As other additives, blue dyes (Dyestuffs) are used. It is easy to determine the coating property such as pinhole, fisheye, crater, etc. during coating inspection, and it mixes auxiliary pigments for color change after exposure, and photo oxidation. Alternatively, as the optical image forming agent, the hardened portion after exposure is colored to give a circuit recognition purpose (workability), and it is a compound which acts on color and image formation, leuco crystal violet colored by acid generation, phenyltribromo methyl sulfone, Dye, such as p-nitro phenyl tribromo methyl sulfone, can be used.

In addition, additives may be optionally used in the LPR composition. For example, hydroquinone, hydroquinone monomethyl ether, phenothianin as polymerization inhibitor, olben, benton as defoamer, deformer and leveler as silicone, fluorine, imidazole, thiazole as polymer adhesion agent, Triazole type, a silane coupling agent, etc. can be used selectively.

The additive usage amount is preferably contained 3 to 5% by weight based on the total composition.

Inorganic fillers may include barium sulfate, barium titanate, silicon oxide, amorphous silica, talc, clay, magnesium carbonate, calcium carbonate, aluminum oxide, aluminum hydroxide, etc. To provide a non-Filler Type LPR.

EXAMPLE

Hereinafter, specific embodiments of the present invention will be described. However, the scope of the present invention is not limited by the embodiment.

In the present invention, the experimental conditions, methods, measuring equipment, and equipment for the LPR composition were set for each process (conditions) as follows.

Clean Room Temperature: 23 ± 2 ℃

Clean Room Relative Humidity: 50 ± 10%

Substrate Pretreatment: Soft Etching or Brush Polishing # 320 ~ # 600

Roller Coater M / C: Burkle company model: DRC4000 / k2 double sided simultaneous coating

              Coating speed: 2 ~ 6m / min (4.5m / min applied)

              Use 48TPI / 90 ° Roll

LPR solid content (%): 45 ± 2%

LPR Viscosity (pa.s): 1.3 ± 0.2pa.s

LPR Coating Thickness (after drying): 10 ± 1 ㎛

Sensitivity: 21step Tabulate stouffer (7 steps)

Art Work Film: Test Pattern:

                          A pattern (Nega: posi = 1: 1, 4: 1)

                          R pattern (Nega: posi = 1: 1, 4: 1)

Pencil Hardness: JIS.K-5400. 614. Pre- and post-exposure measurements (2H / 5H)

Adhesion: JIS D-0202. 8. 12 (Cross cutter 100/100)

                   (3M company, use OPP tape)

Resolution: The resist pattern size should be within ± 20% error range compared to the circuit with the maximum resolution, and the line / space is determined by observing under a microscope.

Viscometer: Brookfield, Model: HBDV-Ⅲ cone / plate Type

                              spindle: cp52

                              Thermostat: TC-500 (25 ℃)

                              speed: 5 RPM

Microscope: Sometech model name ICS-305A

Molecular weight distribution (average molecular weight): Measured by Waters 450 GPC-polystyrene 12129.

Photometer: International Light IL290A

Coating thickness gauge: kett company model: LH-300C

Dryer-IR / hot air step cure or general

              -Drying temperature 80 ± 5 ℃, 90 ~ 120sec of actual substrate surface

            -Holding time after drying (minimum 15 minutes, 48hrs before exposure, up to 72hrs before development)

             -Fully shielded after 6 hours at 2m of Yellow Light.

Exposure: OTS (YH-7090) 5 ~ 8kw Scattering Light Exposure Machine

                   Perkin -Emer TM (5kw) Parallel Optical Exposure Machine (unit mJ / ㎠)

Developer: Concentration 1.0% by weight Na ₂ CO ₃

                   Temperature 30 ± 2 ℃

                   spray pressure: 2kgf / ㎠

                   B.P (Break Point): 55 ± 5%, 1.4 ~ 2 times

                   Minimum development time-No development residue after development.

Stripping: Concentration 2.0 ~ 4.0 wt% NaOH

                    Temperature 45 ± 5 ℃

                     spray pressure 2.0kgf / ㎠

Table 2 shows the synthetic composition ratio of the base polymer.

TABLE 2

Base polymer synthesis shown in Table 2 used azobisisobutyronitrile as a catalyst, propylene glycol monomethyl acetate as a solvent, the reaction temperature of the reaction at 110 ~ 140 ℃ reflux (4 hours), agitation speed 60RPM The polymer was synthesized. The monomer selection depends on the acid value (Acid Value), glass transition temperature (Tg) and molecular weight (MW) of the base polymer.The optimum glass transition temperature is 170 ± 20 ℃, and the acid value is 70 ± 10mgKOH / g. It is preferable that it is 50,000 ± 1,000. Therefore, Example 1 is the most suitable as the base polymer in Table 2, the base polymer of Example 1 is used in the LPR composition of Table 3 below.

If the molecular weight of the base polymer is 80,000 or more or 40,000 or less, it does not have the required properties as LPR, the glass transition temperature is low, and sticking (substrate sticking phenomenon) occurs during storage after coating at room temperature. If it is not suitable for the film, developability and peelability are greatly caused.

The LPR composition was prepared by mixing in the component ratios shown in Table 3 below.

TABLE 3

The LPR composition of Table 3 shows an optimum coating property when a roll coater is applied at a viscosity of 1.3 ± 0.2 pa.s and a solid content of 45 ± 2%, and the drying temperature is appropriate for 2 minutes at 80 ° C. Undevelopment occurs at temperatures above 120 ° C.

The LPR for parallel light shows a 1/2 decrease in sensitivity at about 80 mJ / cm2 of the scattered light LPR, and can distinguish whether or not transfer (scratch generation) is caused by the light wavelength of the light source, and 2,4,6-trimethyl in the photoinitiator Benzoindiphenyl phosphine oxide is suitable for fast curing in the long wavelength region, and benzyl dimethyl ketal is suitable for surface curing in the short wavelength region. The photopolymer has a stickiness after drying of the LPR composition at less than 5 functional groups, and the dipentaerythritol caprolactone hexaacrylate used therein does not exhibit such a phenomenon, and resolution, sensitivity, and long-term storage are suitable.

In particular, it contains 10 to 16% by weight of dipentaerythritol caprolactone hexaacrylate represented by the formula (2) to improve tacky and is suitable for scattering light and parallel light LPR composition having a storage stability for longer than 12 months. Do.

Table 4 shows the resolution according to the exposure conditions.

TABLE 4

The measurement of the resolution (scattered light, parallel light) according to the exposure conditions of Table 4 shows the change of the step and the resolution with respect to the light amount (mJ / cm 2). Sensitivity and resolution may change according to developer concentration, temperature, speed, and coating thickness.The relationship between exposure and sensitivity is that if the exposure is insufficient, the surface of the resist shows erosion after development. It is worn.

The exposure dose is related to energy saving and productivity yield in mass production. In other words, the greater the exposure, the longer the working time and consumes a lot of electrical energy.

According to Table 4, the LPR of the present invention has a resolution up to 20 μm, which indirectly demonstrates that the substrate adhesion of the LPR of the present invention is also compatible.

Table 5 shows the adhesion after drying the LPR coated on the substrate. After cross-cutting the coating surface to generate 100 cells per unit inch (Inch) in each sample was repeated experiments with 3M (OPP Tape). As a result, the adhesion is excellent.

TABLE 5

Table 6 measures the peel properties for the LPR composition. According to Table 6, the peeling characteristics of the LPR composition of the present invention are excellent.

TABLE 6

TABLE 7

Table 7 shows the results of measuring the viscosity of LPR on June 2, 2004 after the LPR composition was formulated at the ratio given in Table 3, prepared on February 10, 2003 (viscosity 1.3 ± 0.2 pa.s), and stored for a long time. to be. As shown in Table 6, there is almost no change in viscosity compared to the time of manufacture. This means that there is little change in the properties of the LPR, and therefore has the same physical properties as at the time of manufacture, so that the storage stability is long-term storage for more than 12 months.

As described in detail above, the LPR according to the present invention has a longer shelf life (12 months) than the conventional LPR, improves the resolution, has excellent adhesion to the substrate, and does not cause tacking during lamination after drying. .

Therefore, when manufacturing PCB by roll coating method, it is possible to manufacture more detailed circuit when manufacturing PCB with conventional DFR or LPR, and it can contribute to yield improvement by reducing defective rate, and it is cheaper than conventional products in terms of manufacturing cost. It can provide about 60% of manufacturing cost when compared per m2.

Claims (4)

20 to 23% by weight of the base polymer represented by the formula (1), dipentaerythritol caprolactone hexa acrylate, which is a photopolymer monomer represented by the formula (2) A negative liquid photoresist (LPR) composition comprising 10 to 16% by weight, 4 to 12% by weight of photopolymerization initiators represented by Formulas 3 and 4, 3 to 5% by weight of other additives, and a residual amount of solvent. [Formula 1]

(R ₁ is CH ₃ or H, R ₂ is an Alkyl group having 1 to 9 carbon atoms, n is the number of polymers) [Formula 2]

[Formula 3]

[Formula 4]

delete delete The negative-type liquid photoresist (LPR) composition according to claim 1, wherein the composition is for scattered light and parallel light having improved shelf life and long term storage stability for at least 12 months.

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